ASTRO 102 Chapter Notes - Chapter 20: Spiral Galaxy, Galactic Center, Observable Universe

• School: U of M
• Department: Astronomy
• Course: ASTRO 102
• Professor: Michael C. Lo Presto

Document Summary

Cosmology - the study of the overall structure and evolution of the universe. What patterns do we find among the properties of. The patch of sky when we observe the universe is an accurate representation of the sky as a whole. Spiral galaxies - flat white disks with yellowish. E. g. , the milky way bulges in their centers. Filled with cool gas and dust, interspersed with hotter ionized gas and usually with spiral arms. Elliptical galaxies - redder, more rounded, and often elongated like a football. Contain very little cool gas and dust, often containing very hot, ionized gas. Irregular galaxies - appear neither disklike nor rounded. The disk component consists of stars and dusty gas clouds that follow orderly, nearly circular orbits around the galactic center. The halo component (sometimes called the spheroidal or ellipsoidal component), generally contains little cool gas and dust, and its stars have orbits with many different inclinations.